Multiple condensed phases in attractively interacting Bose systems

Männel, M.; Morawetz, Klaus; Lipavský, Pavel

doi:10.1088/1367-2630/12/3/033013

Cited by 5 publications

(4 citation statements)

References 22 publications

(46 reference statements)

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“…We use a scheme to eliminate self-interaction in the T-matrix approximation, to calculate properties below the critical temperature [25][26][27][28] . The Green function 29,30 for particles with momentum q and Matsubara frequency…”

Section: A Condensed Phasementioning

confidence: 99%

Coexistence of phase transitions and hysteresis near the onset of Bose-Einstein condensation

2013

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Multiple phases occurring in a Bose gas with finite-range interaction are investigated. In the vicinity of the onset of Bose-Einstein condensation (BEC) the chemical potential and the pressure show a van-der-Waals like behavior indicating a first-order phase transition although there is no longrange attraction. Furthermore the equation of state becomes multivalued near the BEC transition. For a Hartree-Fock or Popov (Hartree-Fock-Bogoliubov) approximation such a multivalued region can be avoided by the Maxwell construction. For sufficiently weak interaction the multivalued region can also be removed using a many-body T-matrix approximation. However, for strong interactions there remains a multivalued region even for the T-matrix approximation and after the Maxwell construction, what is interpreted as a density hysteresis. This unified treatment of normal and condensed phases becomes possible due to the recently found scheme to eliminate self-interaction in the T-matrix approximation, which allows to calculate properties below and above the critical temperature.PACS numbers: 03.75.-b, 67.85.-d

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Section: A Condensed Phasementioning

confidence: 99%

Coexistence of phase transitions and hysteresis near the onset of Bose-Einstein condensation

2013

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“…[7] it was found that both of these phases are unstable against mechanical collapse; that is, the bosons with an attractive interaction tend to form clusters of particles. Moreover, an extension of the mean-field results given in [7,18,19] by the leading-order fluctuation contributions [20,21] or even higher-order corrections [22] to the thermodynamic potential does not lead to a stable homogeneous phase of bosons with the pairing potential. It was observed in [23] that by confining bosons with pairing interactions in a trap, which produces a gap between the ground and the excited states, one can protect the system from the mechanical instability.…”

Section: Introductionmentioning

confidence: 94%

Paired phases and Bose-Einstein condensation of spin-one bosons with attractive interaction

2011

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We analyze paired phases of cold bosonic atoms with spin S = 1 and with an attractive interaction. We derive mean-field self-consistent equations for the matrix order parameter describing such paired bosons on an optical lattice. The possible solutions are classified according to their symmetries. In particular, we find that the self-consistent equations for the SO(3) symmetric phase are of the same form as those for scalar bosons with attractive interactions. This singlet phase may exhibit either the BCS-type pairing instability (BCS phase) or the Bose-Einstein condensation (BEC) quasiparticle condensation together with the BCS-type pairing (BEC phase) for an arbitrary attraction U 0 in the singlet channel of the two-body interaction. We show that both condensate phases become stable if a repulsion U 2 in the quintet channel is above a critical value, which depends on U 0 and other thermodynamic parameters.

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“…The advantage of eliminating only the contributions of single channels as proposed in Refs.[4] and [5] is that the formation of pairs and their condensation can be described within the same approximation. This has also resulted in the description of different phases in interacting Bose systems [7].On the other hand there exist a well established theory to describe systems with condensates in terms of anoma-lous functions, for review see [8]. Let us consider bosonic particles which can form a condensate either bosons or paired fermions.…”

mentioning

confidence: 99%

“…[4] and [5] is that the formation of pairs and their condensation can be described within the same approximation. This has also resulted in the description of different phases in interacting Bose systems [7].…”

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confidence: 99%

Equivalence of the channel-corrected-T-matrix and anomalous-propagator approaches to condensation

Morawetz

2010

Phys. Rev. B

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Any many-body approximation corrected for unphysical repeated collisions in a given condensation channel is shown to provide the same set of equations as they appear by using anomalous propagators. The ad hoc assumption in the latter theory about nonconservation of particle numbers can be released. In this way, the widespread used anomalous-propagator approach is given another physical interpretation. A generalized Soven equation follows which improves a chosen approximation in the same way as the coherent-potential approximation improves the averaged T matrix for impurity scattering.

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Multiple condensed phases in attractively interacting Bose systems

Cited by 5 publications

References 22 publications

Coexistence of phase transitions and hysteresis near the onset of Bose-Einstein condensation

Coexistence of phase transitions and hysteresis near the onset of Bose-Einstein condensation

Paired phases and Bose-Einstein condensation of spin-one bosons with attractive interaction

Equivalence of the channel-corrected-T-matrix and anomalous-propagator approaches to condensation

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